Process of separating graphite from wollastonite.



lilo. 780.297.

,Darren PFairies Patented January l 7, 1905.

PATENT l e sirsrnnn a.

{H/bl. Ul? Pl'nltlNFIiCLll, ANlllfil/XNLEY V. KRM, (lll JERSEY l'lY.,Nillw JERSEY.

l SPECIFICATION' forming part of Lettere Patent No. 780,297, datedJanuary 17, 1905.

Applicatien filed November 16, 1903. Serial No. 181,405.

fo /LZZ wir/(fm, t may concern:

Be it known that we, STEPHEN R. linen', ot i Plainlield, in the countyof Union, and STAN- LEY V. Knorr, of Jersey City, in the county ciHudson, State of New Jersey, both citizens el the United States, haveinvented an .improve nient in the Process oi Separating1 l'flraphitefrom Wollastonite, of which the iolloxfving is a specification.

The material Wollaston-ite treated by our process for the separation etthe flaite or crystalline graphite carried thereby is a mineral composedci about titty-one and seven-tenths per cent. of silica and forty-eightand threetenths per cent.. oi lime ch nically united. (rraphite heldtluireby ir .isually in flake form; and the object ci our inrentirni isto breali nip and destroy the chemical union oi the linie and silica,and so free the graphite. which is 'zo la :ir on used largely`v butnotexclusively, in

the manufacture of erucil'iles.

in the first step oi separat ,5; the graphite from the Wollastonite the`ore is crushed and reduced to a tine granular condition and is thenmechanically separated, preterabl)T by a l pneumatic jig' or d rycencentrator. This separation has the .result of dividing the readily--separable particles-*that is to sav, te the cx tent of about ninety' percent. The process 3o' ot' our invention has especially to do with the.`other tcnper cent. that is, the concentrates--- which still containmore or less woliaetonite.

The reason we are not able to free the graphite entirely,T from thewcllastonite by mechanical means Ais due to the factl that this-rnineral wollastonite is fibrous in its strucn ture and breaks up inneedle-like grains, and some inclosed and adhering particles ot' sichlastonite go over with the graphite. The coarse or heavier grains arereadilyseparated by the mechanical means above referred to; but the verythin or fine needle-like grains tend more or less to go over with thegraphite. 1t isto eliminate these fine needle-like adhering and inclosedparticles of Wollastonite from the graphite to which our invention andprocess relates.

In the particular part of the process foriuing our invention theconcentrated material l is treated to a hath of dilute acid, preferablysulfuric acid, because this acid is not only economical ol* use, butacts entirely satisfactorily. In this bath of dilute sulfuric acid theWollastonite absorbs the liquid, which causes the Wollastonite to swellup, and the chemical bond or union between the silica and linc is b vthis action destroyed1 the acid ab tacliing" the linie and the silica asan insoluble material being; set tree and the linie a soluble materialbeing' turned by the dilute acid into a sulfate ol" linie. The union oithe silica and linie having been destroyed by the action oi the diluteacid` the mineral wollastonite readily crmnlgiles to a fine powder underthe manipulation oi' the hand or mechanical devices and it is preferablein this action. to wash the material thereafter with a liberal supply ofWater in a line-mesh screen, so as to separate the graphite from thesilica, the graphite rernainineM on the screen and the silicaf passing'through the screen. ln this operation the sulfate oi linie under theaction ci' the :water is washed awain leaving` the insoluble silica freeto be removed. lhe dilute sulfuric acid is prefers i abcnt ten per cent.solution. 'llhe chen `inn et l e prec ss is properlji,r exjpre i are olicourse ennjil(iuls uch as tubsior theacid-bath and means for washing thegraphite to clean'it freni the acid and the huur-water, besides screensproperly mounted :ler screening out the powdered silica. 3

.inthe mocos the .vollastonite after being1 treated with the acid fordestroyine` the chem ical bond or union between the silicaand linie maybe Washed and screened for the removal olf the silica or preferablywashed, dried, and then screened for the removal ol. the silica andgraphite.

Vil'hile We have herein described our process as especially applicablefor the treatment of the mineral wollastonite containing lime and silicawith the graphite, We have found that our process is equally valuablefor the treatment of a limestone carrying the graphite and withoutsilica, except the part .of the process that requires the use of -ascreen to free the graphite from the silica. as thereln the washingremoves all the sulfate of lime, leaving i i lute sulfuric acid, therebycausing the wolthe graphite free.

lVhile in carrying out the process we aim to entirely remove the silicafrom thegraphite, so as te leave the graphite commercially pure, we mayremark that a small percentage of silica with the graphite is notinjurious, especially1 where the graphite is used in the manufacture ofcrucibles; but lime is an injurious element.

1n the drawing we have illustrated our process diagrammatically, andtherein a represents a mass of wollastonite; b, the crusher for reducingthe wollastonite to a fine granular condition; c, the mechanicalseparator for concentrating the ore; d, a bath of dilute sulfuric orother acid, in which the material is treated for the destruction of thechemical bond between the silica and lime and the conversion of the limeinto sulfate of lime; e, a washer in which the product is washed toremove the lime.

f represents a drier for the silica and graphite, and gi a separator forthe mechanical separation ofthe silica and graphite, and 7i a vessel toreceive the substantially pure graphite.

l. The process herein described for separating graphite from orescarrying the same, said process consisting in treating the material in abath of dilute sulfuric acid and thereafter submitting the decomposedmixture to a concentrating washing for the recovery of the graphite.

2. The process herein specified for separating graphite from orescarrying the same, said process consisting in crushing the ore to a tinegranularl condition, separating the major portion of the graphit-e fromthe ore by dry concentration, treating the concentrates or residue in abath of dilute sulfuric acid so as to break the chemicalbond or union ofthe lmaterials .treated and thereafter submitting the decomposed mixtureto a concentrating washing for the recovery of the graphite.

3. The process herein described of separating graphite fromwollastonite, the same consisting in treating the wollastonite in a bathof a dilute acid so as to break up or destroy the chemical bond betweenthe lime and silica of the wollastonite, submitting the decomposedmixture to*A a concentrating Washingfor the recovery of the graphiteandv to set the silica free, and thereafter mechanically separating thegraphite from the silica.

4. The method herein specified of separating graphite from wallastonite,consisting in crushing the Wollastonite to a line granular condition,treating the same in a batlrof dilastonite to swell up and the acid toact' for the destruction of the chemical bond between the silica andlime, and converting the lime into sulfate of lime, thereafter washingthe product and washing the lime away, leaving the insoluble silica withthe graphite as a resi due, thereafter treating the graphite and thesilica for the mechanical separation of the same so as to leave thegraphite substantially free from silica.

5. The process herein specified of separating graphite fromwollastonite, consisting in crushing the ivollastonite ore. to a finegranular condition, mechanically separating thel major portion of thegraphite from the ore by dry concentration, taking the ore concentratesand treating the same in a bath of dilute sulfuric acid, thereby causingthe wollastonite to swell up and the acid to act for the destruction ofthe chemical bond between the silica and lime, converting the lime-int-o sulfate of lime, thereafter washing the product and washing'v thelime away,- leaving the insoluble silica with the graphite as a'residue,and thereafter treating the graphite and the silica for the mechanical'separation of the same so as to leave the graphite' commercially pure.

6'. The process herein specified of separating graphite fromwollastonite, consisting in crushing the wollastonite ore to a finegranular condition, mechanically separating the major portion of thegraphite from the ore by dry concentration, taking the ore concentratesand treating the same in a bath ofdilute sulfuric acid, thereby causingthe wollastonite to swell up and the acid to act forthe destruction ofthe chemical bond between the silica andV lime, converting the lime intosul- STEPHEN R. KROM. l STANLEY V. KRM. Witnesses:

GEO. T. PINCKNEY, BERTHA M. ALLEN.

